Conventionally, in order to handle a situation in which a driver cannot see a place of interest due to a blind spot of a vehicle at a time when the vehicle is rolling backward, an image apparatus has been proposed, in which a rear view of a vehicle captured by a camera disposed at the rear of the vehicle is displayed on a monitor at a driving seat.
As shown in FIG. 11, a camera 2 for capturing a rear view of a vehicle 1 is attached to a position at a height h in the vicinity of a number plate 6 at the rear of the vehicle 1. The camera 2 is equipped with a lens and a CCD (not shown), and an image of the rear of the vehicle 1 is captured onto a CCD surface via the lens. A monitor 4 made of a color-type liquid crystal display is disposed at a driving seat of the vehicle 1, and when a shift lever 5 provided at the driving seat is shifted to a backward position, an image captured by the camera 2 is displayed on the monitor 4.
In the above-mentioned apparatus, an image of a road condition and the like at the rear of a vehicle when the vehicle is rolling backward is displayed on a screen of the monitor 4. Therefore, a driver can confirm a rear view by watching the screen of the monitor 4, and then, allow the vehicle to roll backward.
Herein, as shown in FIG. 11, a ground coordinate system is assumed on the ground 10 in which a crossing point between a ground 10 and a camera optical axis 7 that is the center of image-capturing of the camera 2 is an origin O, the rear side of the vehicle 1 is a Y-axis positive direction, and the left side of the vehicle 1 is an X-axis positive direction. A grid line 11 is also assumed on the ground 10, in which lines parallel to the X-axis and the Y-axis are arranged in a grid shape. An image of the grid line 11 captured by the camera 2 on the CCD surface of the camera 2 is as shown in FIG. 12. The image on the CCD surface is displayed on the monitor 4.
However, the camera 2 is mostly attached at a relatively low position in the vicinity of the number plate 6, considering the appearance of the vehicle from its rear side. Accordingly, in the case where the camera is attached at a low position, if an image captured by the camera 2 is displayed on the monitor 4 as it is, a viewpoint of a rear view seen from the screen of the monitor 4 is close to the ground 10, resulting in an image that is difficult to see by human eyes.
Furthermore, when the vehicle is moving, an image movement speed is varied between a region close to the vehicle and a region away from the vehicle on the image of the monitor 4, as shown in FIG. 12, which results in a difficult-to-see image.
Furthermore, as shown in FIG. 12, an image contains lens distortion. Therefore, a straight line drawn on the ground 10 looks like a curved line, which results in a further difficult-to-see image.
On the other hand, the camera 2 cannot be attached in such a manner as to obtain a monitor image from a viewpoint at a position of a rear window 8 of the vehicle 1. Therefore, an image cannot be obtained from such a viewpoint.